Grammar notes: conditionals

General information

In English there are four basic conditional structures, although these can be mixed according to the situation. They can also be mixed in other languages.

The tenses I've used are the BASIC tenses. However, once you know the general structures you can check what other verb forms you can use.

Zero conditional

This is used when there is no condition, in other words you could substitute 'if' with 'when'. It is often used when describing facts or explaining how something works.

Structure: if + present, present

Examples:

If you don't water flowers, they die.
If you turn that switch to the black position, the power gets cut off.
If you mix water with oil, the oil floats.

1st conditional

The first conditional is used for situations based on fact. The condition describes something normal and possible, and the result is probable and based on the present or the future.

Structure: if + present, future

Examples:

If you study hard, you will pass your exams.
If you click on that icon, you'll lose anything you haven't saved.
If it doesn't rain tomorrow we're going to the beach. (present used as future).

2nd conditional

This conditional is not based on fact. It refers to a situation in the present or future which is unreal, unlikely or contrary to facts.

To show this unreality, we have to shift the tense from the present to the past, although the condition still refers to the present or the future.

Structure: if + past, would + infinitive

Examples:

If I won the lottery, I would buy a fast car (but I haven't won the lottery, so I can't buy anything).

If I had some money, I would give you some (but I haven't got any money, so you can't have any).

If Valencia were a good football team I would support them (but they're rubbish, so I don't, and anyway I hate football). OK, so the 2003-4 season was a good one, but let's see what happens in 2004-5.

3rd conditional

The third conditional refers to situations in the past which, because they're in the past, are imaginary or impossible. You can't change the past.

Structure: if + past perfect, would (could/might) have + past participle

Examples:

If I had studied more, I would have passed my exams (but I went out every night with my friends, didn't open a book, and I failed).

If I hadn't spent all my money on CDs I could have given some to you (but I did spend it on CDs and I wouldn't give you any money anyway).

If you had been ready on time, we wouldn't have missed the train and we would have arrived before all the restaurants closed (but you were too slow and now we're hungry and there's nowhere open).